According to me: never enough

According to my wife: way more than necessary

No counting broken bit or stuff I got as props for a photo project:

Large Format

Cambo SC 4x5

Medium format

3 Mamiya M645's (I only really use one; the other two are "insurance".
RB67

Detrola 127 format (does 127 count as medium format?)

35mm

Nikon F3
Nikon FM
Nikon f90s

Pentax ME Super (x2)
2 Exactas
Yashica FX-3
Konica Autoreflex (inherited from father in law)
Leica IIIb
Voigtlander Vito B (inherited from my father; first "good" camera I used, immense sentimental value)
Retina IIa
Olympus Pen FT (needs repair)
Olympus Trip

Maybe my wife is right . . .